1. Field of the Invention
The present invention relates to a high-frequency treatment instrument inserted into a body cavity for incision or coagulation of a living tissue such as mucus membrane with a high-frequency electric current.
2. Description of the Related Art
Recently, surgeries using laparoscope are performed with the purpose of reducing invasion into a patient. In the surgery using laparoscope, a trocar for guiding an endoscope for observation into a body cavity and a trocar for guiding a treatment instrument to a portion to be treated are punctured into an abdominal portion of a patient without abdominal laparotomy, and a treatment procedure is performed while the treatment instrument and the portion to be treated are observed with the endoscope. In this type of surgery, a high-frequency power supply device and a high-frequency treatment device provided with a high-frequency treatment instrument are used. The high-frequency power supply device supplies a high-frequency electric current for treatment such as incision, coagulation and the like for the living tissue of the portion to be treated. The high-frequency treatment instrument is to give a treatment for the portion to be treated.
Also, with an endoscope having flexibility at an insertion portion to be inserted through an oral cavity, an anus or the like, the high-frequency treatment instrument is introduced into the body cavity through a treatment-instrument insertion channel provided to the endoscope for a treatment such as incision, coagulation and the like of the portion to be treated.
The high-frequency treatment instrument is provided with an electrode. When a treatment such as incision, coagulation or the like is to be performed with the high-frequency treatment instrument, the electrode is brought into contact with the living tissue such as mucous membrane and a high-frequency electric current is conducted to the electrode for treatment. When a treatment such as incision, coagulation is to be performed with the high-frequency treatment instrument, the electrode is protruded from a tip end of a sheath, which is the insertion portion having electric insulation. When a coagulation treatment is to be performed on a mucous membrane, an operator brings the electrode conducted with the high-frequency electric current into contact with the mucous membrane and keeps it. On the other hand, at incision or ablation, the operator brings the electrode conducted with the high-frequency electric current to the portion to be treated and moves the electrode in the direction of ablation.
In the high-frequency treatment devices, there are known a monopolar type and a bipolar type.
The monopolar type treatment instrument requires a return electrode in addition to the high-frequency treatment instrument provided with an electrode. The return electrode is brought into surface contact with the surface of the body other than the portion to be treated. The monopolar type treatment device is configured such that the high-frequency electric current outputted from the high-frequency cautery power supply device flows from an electrode provided at the high-frequency treatment instrument via the living tissue, which is the treatment target in contact with the electrode, and returns to the high-frequency cautery power supply device through the return electrode in surface contact with the body surface.
On the other hand, in the bipolar type treatment device, a high-frequency treatment instrument provided with an electrode for treatment and a return electrode is used. The bipolar type treatment device is configured such that the high-frequency electric current outputted from the high-frequency cautery power supply device flows from the electrode for treatment provided at the high-frequency treatment instrument via the living tissue, which is the treatment target in contact with the electrode for treatment, and returns to the high-frequency cautery power supply device through the return electrode. That is, the bipolar type treatment device does not need a return electrode to be brought into surface contact with the body surface.
Japanese Patent Laid-Open Publication No. 8-299355 discloses, for example, a high-frequency knife configured so that puncture into a deep tissue which should not be incised by mistake or unnecessary cautery is prevented during incision of a mucous membrane. This high-frequency knife aims to perform incision by providing an insulating tip larger than the knife at the tip end of the knife for electrode.
Therefore, if bleeding occurs during an incision treatment, it is necessary to replace this high-frequency knife by a high-frequency treatment instrument or the like with excellent coagulation performance and time and labor are required till hemostasis.